a) Thinking the NSA and other intelligence organizations would really make the distinction between US and non-US citizens, except in the scope that public opinion doesn't instantly crush them, doesn't seem like something they'd actually be likely to do.
b) 95% of the earths population are outside of the USA, Facebook alone has a user count higher than 3 times the total US population.
Really, the distinction is completely meaningless for this discussion. The only effect it has is alienating non-US citizens because it makes it seem like US citizens are only concerned about themselves.
I also think the focus on the US surveillance apparatus might not be the way to go either, things like the upcoming Indian surveillance system belong to the very same discussion.